养殖牙鲆性腺分化的组织学观察

Histological observation of gonadal differentiation in cultured Japanese flounder Paralichthys olivaceus

采用切片方法观察了牙鲆Paralichthys olivaceus的性腺发生、性别分化过程及其组织学特征。结果表明:牙鲆仔鱼10日龄(全长约4.2 mm)时观察到原始生殖细胞;20日龄(6.6 mm)时性腺原基形成;30日龄(9.7 mm)时原始性腺形成;50日龄(23.9 mm)时输精管原基形成,精巢开始分化;65日龄(56.1 mm)时卵巢腔形成,卵巢开始分化;85日龄(84.3 mm)时精巢出现精原细胞,精巢分化完成;105日龄(127.8 mm)时卵巢内出现卵细胞,卵巢分化完成。牙鲆雌、雄性腺分化过程差异明显,雄鱼性腺分化早于雌鱼。

The occurrence, process and histological characteristics of gonadal differentiation were histologically observed in Japanese flounder Paralichthys olivaceus. One elliptical primordinal germ cell （PGC） was observed by the 10th day posthatching（dph） （4.2 mm in total length）. On the 20th dph （6.6 mm TL）, the gonad anlage emerged, and remained undifferentiated by 30th dph （9.7 mm TL）. The anlage of the efferent duct was found on the 50th dph （23.8 mm TL）. On the 65th dph （47.5 mm TL）, the dorsal and ventral edges of the gonads began to extend laterally and eventually fused to form the presumptive ovarian cavities along the lateral sides of the gonads. The spermatogonia were first recognized in the testis on the 85th dph （84.3 mm TL） and oocytes in early meiosis were first observed from the 105th dph ovary （124.5 mm TL）, indicating that the sex differentiation is evident distinctness between female and male. The differentiation occurred earlier in male than in female.